This invention relates to auger apparatus of the type that bores deep, laterally extending holes into mineable material in the earth by an auger formed of a string of connected, helically vaned sections, and more particularly to such apparatus providing lower costs of manufacture, increased flexibility, speed and efficiency of operation, and lower cost of transportation and placement of the machine.
The invention provides exceptional advantages when employed in auger mining machines of the type adapted to be positioned adjacent an upwardly extending wall to recover material to be mined from a seam of mineable material such as coal that is exposed in such wall and extends generally laterally into the earth. Therefore, for convenience, the invention will be discussed in connection with such a machine for mining coal, although it may be applicable to other types of auger apparatus.
Auger mining machines of this type comprise an auger embodying a cutting head suitable to the thickness of the coal seam connected to and rotatably driven by a string of endconnected, helically vaned auger sections driven from the machine by being rotated and urged longitudinally of the auger. The cutting head penetrates the coal seam, and the mined coal is transported rearwardly from the cutting head along the auger string by the vanes of the auger sections out of the hole cut by the cutting head to a conveyor on the machine by which the coal is removed.
As the cutting head is caused to penetrate into the hole, it is necessary to introduce auger sections into the string until the desired length of the auger string is reached to achieve the desired depth of hole. After the cutting head has penetrated to the desired depth of hole, it must be withdrawn by removing auger sections until the cutting head is out of the hole. The machine as a whole may then be moved laterally to another position where its auger can drill another hole generally parallel to the previously drilled hole.
The maximum diameter of the auger to be used is largely determined by the thickness of the coal seam, an auger of smaller diameter being used for a thinner seam and an auger of larger diameter being used for a thicker seam. Occasionally, a coal seam that is being mined varies in thickness or in the same wall there are seams of widely varying thickness, or in the locality in which the mining machine is working there are different seams of different thicknesses, so that augers of different diameters should be used for maximum recovery of coal.
It is desirable that a single machine be capable of handling and driving augers of different diameters in order to permit maximum utilization of the machine and maximum recovery of the coal with the single machine without the necessity of bringing in other machines. For a given power output of an auger machine, it is also most desirable that the machine be capable of driving an auger of as large a diameter as feasible.
Moreover, in order to achieve the desired high production, it is necessary rapidly and accurately to handle the auger sections in taking them from a store of sections and placing them in the auger string as the hole is bored, and then in removing the auger sections from the auger string as the auger is withdrawn from the hole. The auger sections are quite heavy, often weighing several hundred pounds or more, particularly those of large diameter. It is desirable that the sections be rapidly lifted and put in place accurately longitudinally and rotationally in the auger string to enable them to be connected preferably automatically to the driving means on the auger machine and to other auger sections in the string when the auger sections are being placed in the string; and to be lifted from and removed from the auger string when necessary after the auger sections are disconnected, preferably by remote control from the driving means and from other auger sections.
Because of the size and weight of the auger sections, they must be handled by mechanical hoist means. The hoist means should be such that it can carry out the above functions rapidly and without danger to an operator. It is important that the operator closely observe the position of the auger section or sections being handled by the hoist means while he is controlling the hoist means to handle the auger sections rapidly and accurately, but that in doing so the operator remain in a safe place free of any danger of being struck by an auger section being moved by the hoist means.
Furthermore, heretofore it has been usually necessary to use at least two operators to handle movement auger sections, one operator controlling the handling of the auger section between an auger string on the machine and the store of auger sections, and another operator being used in connecting or disconnecting the auger sections, while a third operator on the machine controls the rotation of the drive head and the position of the driving carriage longitudinally of the machine. However, for economical operation it is desirable that fewer operators be used to operate the machine and to handle auger sections.
Furthermore, it is usually necessary to cut a floor in a pit to form an essentially vertical wall containing the coal seam. Because auger machines are generally used to mine coal in seams extending in a hill, the pit is generally cut in the form of a ledge in the side of the hill to expose the coal seam. The cost of cutting a pit is substantial, and recent ecological laws and regulations require that substantial backfilling of the pit be performed after the mining operation is concluded, which provides another substantial additional cost. Consequently, it is advisable that the floor of the pit be as narrow as possible to reduce the amount of initial cutting that should be performed, particularly when as is oftend the case considerable rock is encountered, and also to reduce the cost of backfilling. Consequently, it is desirable that the length of the machine be as short as possible to make possible as narrow a pit floor as possible.
Furthermore, it is usually necessary to move the machine from one location to the other either in a certain field of operation, or over the road to mining locations a considerable distance away. The machine, therefore, should be as light as possible and satisfy weight, width, length, and height limitations for over-the-road transportation and for passing under bridges.
Furthermore, it is desirable that the machine be constructed at a cost as low as feasible, and that it be operated economically, efficiently, and with maximum safety to the operators.
All of these factors are desirable to reduce the cost of mining.